1. Field of the Invention
The present invention relates to a dielectric resonator antenna, and in particular to a rectangular dielectric resonator, of which part of the dielectric is removed to form a rectangular caved well, for enhancing electric field and expanding bandwidth.
2. The Prior Arts
A conventional dielectric resonator antenna is usually made of a material with high dielectric constant and low loss. The dielectric resonator antenna has many advantages, for example, high radiation efficiency, simple structure, and various radiation patterns achieved by stimulating various modes. However, it is a resonator antenna, and its bandwidth is limited. Basically, the dimensions and shape of the antenna decide the operating frequency and the bandwidth of the resonator antenna.
The means to increase the bandwidth of the dielectric resonator antenna include: (1) cutting off the apex of a conical dielectric resonator, making the smaller cross-section grounded, and using a probe to feed in, thereby achieving about 40% of bandwidth; (2) increasing the ratios of length to height or width to height of a rectangular parallelepiped dielectric resonator, which may also increase the bandwidth; (3) piling a plurality of dielectric resonators with various sizes and resonant frequencies close to each other, thereby combining the operating bandwidth to increase the bandwidth; (4) mounting a dielectric resonator above a patch antenna, and providing a slot on the patch antenna, thereby feeding energy into the dielectric resonator and combining the operating bandwidths of these two antennas to increase the bandwidth; (5) coating a metal layer on a dielectric resonator to incur extra resonance, and making the resonant frequency close to the frequency of the dielectric resonator, thereby extending the bandwidth of the original dielectric resonator antenna. All these methods increase the complexity of the manufacturing process and the cost. Therefore, the present invention carries on the improvement on the bandwidth limitation of the dielectric resonator antenna.